John Shepherd, cardiovascular expert, dies at 92

MINNEAPOLIS (Reuters) - Dr. John Shepherd, whose discoveries have led to new ways to treat high blood pressure and who helped astronauts withstand the rigors of space travel, has died, his family and colleagues said on Friday.

Shepherd, who had suffered from Alzheimer's disease, was 92 when he died on Tuesday at the Mayo Clinic in Rochester, Minnesota, where he began working full time in 1957 after immigrating from Northern Ireland.

Born in 1919, Shepherd was the son of a Presbyterian minister and became one of 15 physicians in his family.

A colleague at the famed Mayo Clinic, Dr. Michael Joyner, said Shepherd was one of the top cardiovascular researchers of the past half-century.

Shepherd's work revealed how the nervous system, and not just the kidneys, was vital to blood pressure regulation.

"He made fundamental observations about how the nerves control blood pressure, and that has led to all kinds of ideas and therapies for hypertension," Joyner said.

Among them are pacemaker-like devices under development to regulate malfunctioning baroreceptors in the neck, which help the brain interpret the body's blood pressure but can get out of whack like a broken thermostat that keeps turning up the heat, he said.

Some of Shepherd's research findings in the 1950s, 1960s and 1970s are only now bearing fruit as the technology catches up, Joyner said.

Shepherd's research caught the attention of the U.S. space program, which was struggling with the problem of astronauts fainting upon returning to Earth, and suffering from reduced bone mass and atrophied muscles due to weightlessness.

Shepherd, working with counterparts in the then-Soviet Union, "came up with some countermeasures ... exercise protocols (still) used in outer space, and fluid-loading and salt-loading that have been quite helpful," Joyner said.

That work led to Shepherd's hobby collecting space-themed stamps, and he had one of the world's largest such collections, his family said.

Shepherd became president of the American Heart Association in 1975, and worked closely with the National Academy of Sciences for years.

Joyner said Shepherd was largely responsible for transforming the Mayo Clinic from exclusively a treatment facility to an academic and research institution.

He arrived at the clinic in 1953 on a Fulbright Scholarship. He chose Mayo based on his brother's enthusiasm after reading the book "The Doctors Mayo."

"He had perfect manners, always wore nice suits, but beneath that was an incredibly curious individual who was willing to challenge conventional wisdom," Joyner said.

Shepherd is survived by his second wife, Marion, a son and daughter, four step-children, five grandchildren, eight step-grandchildren and a great-grandson.